[PATCH 4.17 52/63] sctp: introduce sctp_dst_mtu

From: Greg Kroah-Hartman
Date: Mon Jul 23 2018 - 08:27:45 EST


4.17-stable review patch. If anyone has any objections, please let me know.

------------------

From: Marcelo Ricardo Leitner <marcelo.leitner@xxxxxxxxx>

[ Upstream commit 6ff0f871c20ec1769a481edca86f23c76b2b06d3 ]

Which makes sure that the MTU respects the minimum value of
SCTP_DEFAULT_MINSEGMENT and that it is correctly aligned.

Signed-off-by: Marcelo Ricardo Leitner <marcelo.leitner@xxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
include/net/sctp/sctp.h | 9 +++++++--
net/sctp/associola.c | 6 ++----
net/sctp/transport.c | 6 +++---
3 files changed, 12 insertions(+), 9 deletions(-)

--- a/include/net/sctp/sctp.h
+++ b/include/net/sctp/sctp.h
@@ -609,10 +609,15 @@ static inline struct dst_entry *sctp_tra
return t->dst;
}

+static inline __u32 sctp_dst_mtu(const struct dst_entry *dst)
+{
+ return SCTP_TRUNC4(max_t(__u32, dst_mtu(dst),
+ SCTP_DEFAULT_MINSEGMENT));
+}
+
static inline bool sctp_transport_pmtu_check(struct sctp_transport *t)
{
- __u32 pmtu = max_t(size_t, SCTP_TRUNC4(dst_mtu(t->dst)),
- SCTP_DEFAULT_MINSEGMENT);
+ __u32 pmtu = sctp_dst_mtu(t->dst);

if (t->pathmtu == pmtu)
return true;
--- a/net/sctp/associola.c
+++ b/net/sctp/associola.c
@@ -1446,11 +1446,9 @@ void sctp_assoc_sync_pmtu(struct sctp_as
return;

/* Get the lowest pmtu of all the transports. */
- list_for_each_entry(t, &asoc->peer.transport_addr_list,
- transports) {
+ list_for_each_entry(t, &asoc->peer.transport_addr_list, transports) {
if (t->pmtu_pending && t->dst) {
- sctp_transport_update_pmtu(
- t, SCTP_TRUNC4(dst_mtu(t->dst)));
+ sctp_transport_update_pmtu(t, sctp_dst_mtu(t->dst));
t->pmtu_pending = 0;
}
if (!pmtu || (t->pathmtu < pmtu))
--- a/net/sctp/transport.c
+++ b/net/sctp/transport.c
@@ -242,9 +242,9 @@ void sctp_transport_pmtu(struct sctp_tra
&transport->fl, sk);
}

- if (transport->dst) {
- transport->pathmtu = SCTP_TRUNC4(dst_mtu(transport->dst));
- } else
+ if (transport->dst)
+ transport->pathmtu = sctp_dst_mtu(transport->dst);
+ else
transport->pathmtu = SCTP_DEFAULT_MAXSEGMENT;
}